Dynamic response of articulated towers under correlated wind and waves

This paper deals with the dynamic behavior of a double-hinged articulated tower to wave alone, and correlated wind and waves. The analysis includes the nonlinearities due to nonlinear drag force, fluctuating buoyancy, variable added mass and instantaneous tower orientation. The fluctuating wind load is modeled by Ochi and Shin spectrum, while the wave load is characterized by Pierson-Moskowitz (P-M) spectrum. The nonlinear dynamic equation of motion is derived by Hamilton's principle. The equations of motion are solved in time domain by using Wilson-theta method. Power spectral density function (PSDF) of surge, tilting motion, hinge shear and bending moment are presented under high, moderate and low sea states. Studies of correlated wind and waves are found to be imperative for double hinged articulated towers to serve and survive in the extreme ocean environment. The response PSDF highlights the wind induced dynamic responses of the tower.